Erosion Control March/April 2017 : Page 16

The Science of Seeds Experimentation produces the right combinations of soil amendments and seed mixes. BY BARBARA HESSELGRAVE R emember how 10 blindfolded people in a room each describe the elephant from their own perspective? The same might be said of soil—the stuff we interchangeably refer to as ground, dirt, or surface covering. Eric C. Brevik, a professor of soil science at Dickinson State Uni-versity in North Dakota, illustrates how soil by any other name is not just dirt. In a chapter of the book Land Use, Land Cover and Soil Sciences , he says a geologist would define soil as a medium to grow plants; an engineer might say it is “all unconsoli-dated materials above bedrock;” and a soil scientist would call it “living matter to support plant life that arises from biogeochemical and physical weathering.” And yet, for those who manage erosion, soil is more often than not a really big headache—both to get it where it needs to be, and to move it away from where it causes problems. While current management practices are helped by the latest science and technology, much of what we do today is not new. Fertilizers, seed treatment, and soil amendments are all erosion management practices built on centuries of previous experiments by civilizations that precede us, some by thousands of years. Manuscripts from as early as 800 B.C. show that the Phoenicians constructed bench terraces on steep slopes and practiced a cultivated, irrigated agriculture on these terraces. The early Britons and the Chinese also practiced terracing by the 7th century A.D. Early farmers knew that crop rotation, planting of legumes, and spreading green and composted manure increased soil productivity. Although the basics of managing erosion by restoring plants to the soil have not changed—soil is prepared, seeds are planted and covered with protective materials—our latest techniques are nevertheless pretty remarkable. Prioritizing the Damage “It was sloughing at such a rate we were losing property,” says Molly Trujillo, capital improvements projects manager with the Southeast Metro Stormwater Authority (SEMSWA), describing the Piney Creek stream restoration in Centennial, WWW.EROSIONCONTROL.COM 16 EROSION CONTROL ISTOCK/BENIHIMEART